RainsFire

katana q's.. again..

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so, just finished hammering out my katana blade, 28in long plus the tang.. 1050 hc alloy. And im wondering how I put in the Bohi (blood grooves) do I grind them? hammer them in? I saw someone on youtube using a small punch type tool to engrave the grooves but I dont know if thats the only way..

can you get cotton wrap for the handle from anywhere local? or do I have to mailorder it?

Thanks-

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Katanas do not have blood grooves. They don't need them, they're very light weight weapons, and not often used for stabbing thus blood grooves were never used on them. Katanas are incredibly complex weapons. I recommend you study them in depth before you attempt to make one.

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Bohi, groves in the katana are fairly common, Derek; perhaps *you* should do some studying. No sword needs "blood grooves"; but fullers do help to lighten a weapon without subtracting much strength. Some styles of japanese sword use like Bohi due to the sound they make when swinging the blades---you know when you are doing it right when the blade makes the proper sound. (would have to be figured out for each blade I would think.) Sometimes Bohi or carving can be used to deal with cosmetic flaws along the back of the blade.

They are traditionaly cut into the surface---remember that the back of the blade is soft after heat treat, using a variation on a sen, a drawknife for metal. The grove maker has a chisel shaped tooth to it and by firmly mounting the blade and then applying the correct ammount of pressure and drawing the sen along the blade you gradually "plane" the grove in. Just starting out I would suggest you don't fully shape it to leave room to clean it up with proper shaped stones or with silicon carbide paper wrapped around sections of dowel.

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Hello:

In answer to your question, the Hi (groove) was usually scraped in with a sen (a kind of draw knife/gouge tool) It takes a while as you are cutting steel but it does do the job.

These are not "blood grooves" they are there to lighten the blade without sacrificing any noticable strength..Japanese swords of the period were a bit on the heavy side, cross section wise and well a fuller/groove cold help with that. They also have another more subtle purpose in that they can also "remove" any forge flaws in the area that they run through.

I have a feeling that you are getting in over your head here, so take it slow..

Contrary to the above post the Japanese sword is not all that complex..it is just composite construction. The European smiths were doing much more complex forgings 500 to 800 years before the Japanese even started.

Now the unique thing about the Japanese style of blade making, especially in sword, was the thermal treatment. That takes some skill and a whole lot of practice to get it right///

JPH

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I'm sorry I have never seen a katana with a blood groove, or fuller so I assumed.

I am aware that groves are not created to release pressure when you stab some , but to make the sword light weight.

I could debate that katanas are complex, but I haven't studied other swords so I have nothing to compare with. I came here to learn, forgive my ignorance.

I have only studied the modern katana, not the older forms of the weapon.

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Thanks guy's, Im takin it kinda slow.. I think, and im taking a few shortcuts.. (using a grinder's the big one) I kinda hammered the blade a bit thin, so the Hi will be shallow.. and more for asthetics anyway..

I didn't think the term blood groove was right.. I just couldn't think of the proper english term at the moment and figured you guy's would know what im talkin about..

so yup, thanks ya'll

OH, and also.. on a katana is there a double bevel? or does the blade just taper down at 30'ish degrees all the way? I really should brush up on my japanese sword terms... I know that it is parallel, goes to the angled part with the hamon and such, but then does it have another more obtuse angle for sharpness?

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Rains:

On the bevel...man you need to get ahold of a couple of books you are going into this blind...

OK...I have seen swords that were triangular in cross section, some were five sided, some were 7 sided...all depends upon when it was made, who made it and where. There's no hard fast rules to old swords when it comes to making them now... Some had Hi, some had more than one...some had none..this is pretty much open to interpetation..

Get ahold ok Kapp's "The Craft of the Japanese Sword"..it's one of the best books out there right now..

I am in the middle of doing a naginata in sword mounts right now...what a PITA but this is for book 4 so....

JPH

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I second getting "Craft of the Japanese Sword" definately a good book for beginners. NO BS, just good info. Or wait for Jim's book:D.

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so, Im wondering something that you guy's could probably help me out on.. For the hamon, do I have to make the same pattern on each side Identical? this seems difficult but I cant see any other way of doing it..

yep, so please lmk.. I ordered craft of the japanese sword, so it'll be here soon..

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phew, then its close enough.. I was being dumb and coated the entire thing with refractory cement(experiment) then it hardened.. so I had to grind out the hamon line, which actually worked really well. I think I'll have a super sharp hamon if it works at all.. I think I'll temper it tonight.

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Traditional katanas were not generally tempered they were just hardened; but that is with their very shallow hardening steel. Modern steels will generally profit from some tempering after hardening even if it's a low ammount.

Remember Harden first and then Temper---two seperate procedures. The hamon is a sign of differential *hardening* not tempering! (this is often gotten wrong by people who don't know the proper terms for the heat treat processes)

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right, IM one of those guy's that get the wording confused every once in a while.. But in practice I know the difference.

thank you all for your help, and I think I will have some pictures of the hamon here shortly if it was a success.

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